Ventricular Arrhythmias Flashcards
What is indicative of ventricular ectopy on ECGs?
wide and bizarre QRS
- wide because it takes longer to depolarize
- premature, late
- NOT initiated by P waves
How does ventricular ectopy compare to BBB?
BBBs are preceded by P waves
What primary cardiac diseases and metabolic/endocrine diseases can cause centricular arrhythmias?
CARDIAC = cardiomyopathies, infectious, inflammatory (myositis)
ENDOCRINE = K, Mg, Ca, hyperthyroidism
What drugs and toxins can cause ventricular arrhythmias?
- Digoxin
- Amphetamine
- Theobromine
- Albuterol
What conditions commonly cause ventricular arrhythmia?
- ischemia
- GDV
- sepsis
- splenic disease
- hypoxia
- hypovolemia
- trauma
- pain
- decreased sympathetic innervation - inherited arrhythmias in GSDs
- increased sympathetic innervation - pheochromocytoma
What is the difference between ventricular premature contraction and escape beats?
VPCs = early, randomly placed ventricular beat interrupting normal rhythm
ESCAPE BEAT = late, preceded by a pause where the heart is trying to compensate
What is indicative of a singlet ventricular premature complex (VPC) on ECG?
wide and bizarre QRS complex not initiated by a P wave
- come early and followed by a compensatory pause
What are the most common causes of VPCs in dogs and cats? What treatment is recommended?
- DOGS = large breed cardiomyopathy (Boxers, Dobermans)
- CATS = cardiomyopathy, hyperthyroidism
- congenital disease, CVD, GDV, myocarditis, anesthesia, infiltrative neoplasia, traumatic myocarditis, digitalis toxicity
a few VPCs once in a while can be acceptable in some breeds, but cause should really be investigated and treated (look at ECG > 30s)
What is occurring in this ECG?
VPCs
- wide and bizarre QRS complex not initiated by a P wave
What is occurring in this ECG?
sinus rhythm interrupted by 3 single VPCs
How can the ventricle of origin be differentiated with VPCs on ECG?
RIGHT VENTRICLE = mostly positive QRS
LEFT VENTRICLE = mostly negative QRS
What are some causes of right and left sided disease that can cause VPCs? What most commonly causes disease on both sides?
RIGHT VENTRICLE = arrhythmogenic right ventricular cardiomyopathy (ARVC) in Boxers and Bulldogs, less common (positive QRS)
LEFT VENTRICLE = DCM (Dobermans, Irish Wolfhound, Great Danes), HCM (cats), more common (negative QRS)
EITHER = diffuse myocarditis or myocardial infiltration
VPCs, complexity:
What is occurring in this ECG?
couplet VPCs
What is occurring in this ECG?
one VPC
What is the R on T phenomenon? What 2 things does it indicate?
QRS fires very closely to the preceding T wave
- high risk for development of ventricular fibrillation
- anti-arrhythmic therapy warranted
What is accelerated idioventricular rhythm? How does it appear on ECGs?
runs of VPCs at a rate less than 160 bpm and greated than 40 bpm
- 4 or more VPCs
- looks like VTACH, but much slower
What is occurring in this ECG?
idioventricular rhythm
- 4 VPCs
- HR = 40-160 bpm
What is an accelerated idioventricular rhythm (AIVR)? Is treatment necessary?
slow ventricular tachycardia —> alternation between VPCs and normal sinus rhythm
benign arrhythmia - does not perturb hemodynamics, tx not necessary (without ECF, likely nothing was noted wrong with the heart)
What is occurring in this ECG?
accelerated idioventricular rhythm
- VPCs alternate with normal sinus rhythm
What causes ventricular tachycardia? What 2 things are seen on ECGs?
stimulation of an ectopic ventricular focus
- runs of > VPCs @ >160-180 bpm sustained for > 30s
- QRS complexes with no relationship to P waves (hidden)
When does ventricular tachycardia affect heart function? Why are they especially serious? What conditions are associated?
300 bpm >6-8 bpm
can be pre-fibrillatory and has direct effects on the heart and secondary organs due to poor perfusion
- large dogs with DCM
- uncommon in cats
What is occurring in these ECGs?
sustained ventricular tachycardia
What are 2 signs of ventricular fibrillation on ECGs?
- rapid, chaotic, irregular rhythm with bizarre waves or oscillations
- no QRS or P waves (large = coarse, small = fine)
What is occurring in this ECG?
ventricular fibrillation
What treatment is recommended for ventricular fibrillation?
quick treatment with Epinephrine +/- electrical defibrillation (transthoracic vs. internal) +/- magnesium to stabilize resting membrane potential
- no treatment = likely death
What is ventricular asystole? What is indicative on ECG?
terminal rhythm due to no pacemaker impulse = no contraction, no pulses, no cardiac output with severe sinoatrial block or arrest
no QRS complexes
What is occurring in this ECG?
ventricular asystole
Ventricular arrhythmias:
